Detection of hybrid Pyganodon grandis and P. lacustris (Bivalvia: Unionidae) using F- and M-type mitochondrial DNA sequences and geometric morphometrics

Abstract

Pyganodon grandis and P. lacustris, widespread and common species in North America, are known to co-occur across parts of their distributions. These mussels are genetically distinguishable with a sequence divergence between 9% and 13% for the mitochondrial (mt) DNA barcoding region, cytochrome c oxidase subunit I (COI), which is well beyond thresholds for distinct species. The objectives of this study were to (1) confirm the presence of two genetically distinct species (P. grandis and P. lacustris) in Font Lake and Lake Geneserath on Beaver Island in northern Lake Michigan, (2) identify hybrids using mitogenotype mismatch and (3) compare species and populations morphometrically. Of the 212 specimens sequenced, 146 (68.9%) were found to be heteroplasmic, with successful amplifications of both maternally (F-type, from mantle tissue) and paternally (M-type, from gonad tissue) inherited mt DNA sequences. Mismatches in species identity of the F- and M-type COI sequences were found in 22 specimens (15.1% of heteroplasmic specimens), with these being considered putative hybrids. Geometric morphometric analyses of shell shape reliably differentiated specimens by species (identified using COI sequences) and between lakes, correctly assigning 97.4% of homoplasmic and heteroplasmic specimens with matching mitogenomes to both species and lake of origin. The shape of putative hybrids generally resembled those of the F-type mt DNA sequence that was recovered. This study confirms that hybridization does occur between sympatric Pyganodon species. Additionally, our results reemphasize the value of modern morphometric techniques for distinguishing among species and populations with overlapping morphological variability.

Discordant population structure inferred from male- and female-type mtDNAs from Macoma balthica, a bivalve species characterized by doubly uniparental inheritance of mitochondria

“…However, counter examples do exist. For instance, Beauchamp et al (2020) found more F-type haplotypes than M-type haplotypes in Pyganodon grandis (11 and 7, respectively) and P. lacustris (20 and 6, respectively). Smietanka et al 2013 (87 F- and 76 M-type haplotypes in Mytilus trossulus ) and Riginos et al 2004 (132 F- and 56 M-type haplotypes in Mytilus edulis ) reported the same pattern, although the latter results might be due to the difficulty of amplifying the male-type mtDNA.…”

“…Most hypotheses on the role of selection, mutation and effective population size in shaping genetic diversity in DUI bivalves remain to be empirically tested.However, counter examples do exist. For instance,Beauchamp et al (2020) found more F-type haplotypes than M-type haplotypes in Pyganodon grandis (11 and 7, respectively) and P. lacustris (20 and 6, respectively).Smietanka et al 2013 (87 F-and 76 M- type haplotypes in Mytilus trossulus) andRiginos et al 2004 (132 F-and 56 M-type…”

Morphometric Analyses Distinguish Wabash Pigtoe (Fusconaia flava) and Round Pigtoe (Pleurobema sintoxia) Mussels

“…Morphometric analysis has also advanced considerably over the last 30 years with the development of landmark-based morphometric analyses making the quantification of shapes much more rigorous and reliable [15]. Modern morphometric analyses, in combination with DNA barcoding, has the potential to greatly clarify and quantify differences between morphologically problematic and difficult to identify species; these techniques have been applied to freshwater mussels and have proven useful for aiding in identifying morphologically difficult species [16][17][18][19] and near-microscopic juvenile mussels [13].…”

Conservación de las poblaciones de bivalvos nativos (Mollusca: bivalvia: unionoida) en Argentina

“…Los análisis de morfometría geométrica fueron ampliamente utilizados en unionoideos (Bailey & Green, 1988;Beauchamp et al, 2020;Beyett etal., 2020;Cano-Otalvaro et al, 2012;Echem et al, 2016;Fassatoui et al, 2015;Inoue et al, 2014;Jeratthitikul et al, 2019;Keogh et al, 2019;Morais et al, 2014;Troncon & Avelar, 2011;Zieritz & Alridge, 2009Zieritz et al, 2010). Autores como Baker et al (2003Baker et al ( , 2004…”

“…La información taxonómica precisa sobre los unionoideos cobra vital importancia en términos de conservación, como ya se explicó en la sección 1.4. La morfometría geométrica es un método que ha sido utilizado en unionoideos (Bailey & Green, 1988;Beauchamp et al, 2020;Beyett etal., 2020;Cano-Otalvaro et al, 2012;Echem et al, 2016;Fassatoui et al, 2015;Inoue et al, 2014;Jeratthitikul et al, 2019;Keogh et al, 2019;Morais et al, 2014;Troncon & Avelar, 2011;Zieritz & Alridge, 2009Zieritz et al, 2010). Si bien se probó su capacidad para distinguir especies cercanas, esta herramienta no ha sido aún utilizada para resolver las discrepancias taxonómicas dentro del género Diplodon.…”